dr davy's miscellaneous observations on the blood. 35 



disease, are not of unfrequent occurrence, and this often without any apparent 

 lesion in the coats of the vessels themselves, or in the lining membrane of the 

 ventricles. 



4. Confirmatory of the last, many examples are on record of the blood, in its 

 coagulated state after death, having been found broken up in the left ventricle of 

 the heart, proving that its coagulation must have taken place whilst the heart 

 was still forcibly acting, and this in cases in which the organ appeared to be 

 sound* 



5. Certain poisons influence the coagulation, some accelerating it, some retard- 

 ing it. As an example of both, may be mentioned the poison of a snake, the 

 tic-polonga of Ceylon (Daboia Bussellii, Gray), which on fowls acts with extreme 

 rapidity, so much so, that simultaneously with their death, it occasions the 

 coagulation of the blood in the heart and great vessels, and this even before the 

 former has ceased to act ; whilst, in larger animals, such as the dog, in which it 

 takes effect less rapidly, causing death in an hour instead of about a minute, it 

 has a contrary influence, that of preventing the coagulation of the blood.f There 

 are other considerations which seem to me to cast a doubt on the accuracy of this 

 hypothesis. To reconcile it with certain facts, its author is under the necessity 

 of assuming that a clot is a " living tissue in relation to the blood ;" if so, then 

 does it not follow, in strictness of reasoning, that such must be its state under all 

 conditions, whether formed within the body during life, or in blood abstracted by 

 the ordinary operation of blood-letting ; and he is further under the necessity of 

 assuming that inflamed parts are quasi dead parts, or, in other words, — and they 

 are his — " have lost for a time their vital properties, and comport themselves like 

 ordinary solids." 



The vagueness, moreover, of the hypothesis renders it open to objection. The 

 referring the phenomenon to a catalytic action, seems to be little more than the 

 accounting for what is obscure by that which is equally or hardly less obscure. 



To conclude, I fear it must be confessed that, strictly speaking, the theory of 

 the coagulation of the blood, its vera causa, is still an unsolved problem, there 

 being, to all the hypotheses which have hitherto been propounded, opposing facts 

 logically in strictness prohibiting the establishment of any one of them. 



* Seethe author's Anatom. and Physiolog. Research., ii. 196. f Idem, vol. i. p. 123. 



VOL. XXIV. PART I. K 



